A ballot measure that would require electric companies to get half their power from renewable sources is trailing by about 13 percentage points, while almost one-fifth of voters are undecided, according to a poll from Suffolk University and The Arizona Republic.

Proposition 127, which is on November’s ballot, would require the boost in renewable-energy sources, like solar and wind, by 2030. It would be a big jump from the 8 percent renewable-energy standard utilities face today (it will rise to 15 percent in 2025 under current regulations).

The poll found that 46.6 percent would vote no on Prop. 127, while 33.6 would vote yes.

The ballot measure is financially backed by California activist Tom Steyer and his group, NextGen America. It is widely opposed by utilities such as Arizona Public Service Co. and a variety of groups concerned it could raise electric bills.